This invention relates primarily to circular vibratory fluid bed processors typically used for heating and drying or cooling particulate food materials, or the like.
In a typical, prior art circular vibratory fluid bed dryer, air is taken from the outside and heated while material to be dried is introduced to the apparatus. Hot air is brought up through the bed or deck, where the material is vibrating, fluidizing the material to be dried, so that there is intimate contact between the hot air and moist product. The heated air drives off the moisture and the dry product moves to an exit where it is discharged. The energy requirements for such a process are not necessarily governed by what is needed to drive off moisture from the material; the requirements instead are governed by the amount of heat required to heat the amount of incoming air, which is required for fluidization of the moving particals on the vibrating bed. A great deal of heat can be wasted in the exhaust air.
It would be a significant improvement in the above generally described state-of-the-art if, in the same footprint, a significant increase in materials processed would be enabled by using a multi-deck system, herein described as a two-deck system, but not necessarily limited to two decks.
A similar improvement would result from a multi-deck system with only a small increase in the size of the fan used typically in apparatus to move the air for drying or cooling food materials, pharmaceuticals, chemicals or other products. Still further, in a multi-deck system, there is only a slight increase in the amount of heat that would be required since the volumetric air flow is essentially the same for single and multi-deck processing; hence less energy is required per pound of product processed in a two deck unit used to dry approximately twice as much material. Additionally, materials dried in the present invention two-deck system travel in the processing from the upper deck to the lower deck; and air moves from below the lower deck, through the lower deck and then upwardly through the upper deck. A one-way valve and structure is used to carry the material, partially dried, from the upper deck downwardly to the lower deck for completion of the drying and the output of the dried materials.
The prior art fluid bed dryers in existence today, use more energy for amount of material processed and require larger capacity air flow per square foot of drier bed fluidization than is required in a multi-deck unit, which uses the same air velocity for fluidization and heat transfer. Also, if the prior art fluid bed dryers do have multi-decks, they are not vibratory, and therefore, the particles are dependent solely on the upward air velocity for fluidization and hence greater air flows, more heat and thereby more energy to accomplish their processes.
Accordingly, a primary object of the present invention is to provide a circular vibratory fluid bed dryer with two or more decks, for efficiency of energy required for air and heat and for efficiency in processing higher production rates within the same footprint.
A further object is to provide a circular vibratory fluid processor for drying or cooling, which is more efficient than single bed dryers or coolers, or than double bed dryers or coolers, which do not use vibration.
These and other objects of the present invention are provided in a circular vibratory fluid bed dryer which features a pair of decks located in the space between the air intake port and the material inlet port located at the top of the apparatus, adjacent to the air outlet port. The apparatus elements are located in such a way, and with the friction of the air going through the very small apertures defined by the upper deck itself, to create a pressure drop from below the upper deck to above the upper deck. The pressure drop enables the use of a one way valve to carry the material from above the upper deck to the lower deck, thereby to prevent the air flowing upwardly from blocking the downflow of material in the apparatus and bypassing the upper deck. The input of material from above the upper deck is of partly dry material, which gives up moisture to the air above the top deck to the process of fluidization and the heat transfer between the vertically rising heated air flow being in intimate contact with moisture laden particles. Completion of the drying is on the lower deck.
As the air inlet provides heated air below the lower deck, and vibration of the entire apparatus causes the material particles to commence movement and thus require less air to accomplish fluidization, the thermal efficiency of the drying apparatus is increased.
Similarly, a cooling system is enabled by the same apparatus.